Description
Secretory IgA (sIgA) is an immunoglobulin formed by plasma cells located in the lamina propria.
sIgA consists of two IgA monomers joined by the J-chain and an additional secretory component. Synthesis of sIgA is independent from the synthesis of serum IgA. This means that lack of serum IgA does not necessarily correlate with a lack of sIgA1. sIgA plays a crucial role in the immune function of the mucosa. It serves as a first line of defence of the mucous membranes against pathogenic germs, enteric toxins, and food allergens. In healthy people, sIgA covers the mucosa in a protective layer and therefore occurs in body secretions. sIgA is the major immunoglobulin in saliva, tears, colostrum, nasal mucous, mother’s milk, tracheobronchial and gastrointestinal secretes. It plays a major role in preventing adherence of microorganisms to mucosal sites, in activation of the alternative complement pathway, and in activating inflammatory reactions.
Determining sIgA concentrations in stool provides information about the activation and secretion rate of the intestinal plasma cells located in the lamina propria, thus allowing to draw conclusions about the status of the immunological barrier of the intestinal mucosa.
